Designers in London created 'Sammy Screamer' sensor to be attached to objects so that itcan alert owners if they are moved.(Daily Mail - Science, 6 February 2014)

Uber–along with competitors Lyft, Sidecar and Zipcar–uses GPS technology to alert an army of paid citizen drivers to passengers who need a ride.(Forbes - Business, 11 November 2014)

Police have obviously been expecting this when they boosted Australia's terroristalerta few months ago, but "lone wolf"-style attacks still represent their worst nightmare, experts say.(Sydney Morning Herald - National, 15 December 2014)

Negative sentences with the verb Alert

2 examples:

A birddoesn't alert his fellow bird that a stone is coming.(African proverb)

A Toronto-area hospital didn't alert police after allegations were made that a staff member sexually assaulted at least five elderly patients, CBC News has learned.(John Lancaster and Jennifer Fowler in CBC News - Health, 9 March 2016)

Questions

5 examples:

To be alarmed, or just alert?(Sydney Morning Herald - National, 25 September 2014)

Obviously, you alert someone nearby or call an ambulance, but then what?(Daily Mail - Health, 13 July 2015)

Consumer Alert: Unless you are a day-trader, why should you care where oil prices are today or where they will be tomorrow?(Forbes - Personal Finance, 24 February 2015)

SPOILER ALERT: In GoT's season six, episode three, a plethora of young Starks, little birds with new purpose and just what was in that tower?(Sydney Morning Herald - Entertainment, 9 May 2016)

Ever wish your bike could give you directions while you ride, turn on a motor to give you a boost up steep hills, or alert you if someone tries to steal it from its parking spot?(Emily Chung,Aaron Saltzman in CBC News - Business, 2 September 2015)

Other sentences

100 examples:

Stay alert.

Look alert.

Just keep alert.

Everyone was alert.

Try and stay alert.

We have to stay alert.

You need to stay alert.

Stay quiet and be alert.

We've got to stay alert.

We must be alert to dangers.

Tom forced himself to stay alert.

Be alertwhen you cross a busy street!

500 policemen were put on strict alert.

I forced you to be to present and alert.

Drinking coffee may help you stay alert.

He is alert to every chance of making money.

I feel more alert after drinking a cup of coffee.

Spend everyday casual, but industrious Every momentalert, but relaxed.(Guy Finley)

Be alert to give service. What counts a great deal in life is what we do for others.

If you have a priest that is pushing social justice, go find another parish. Go alert your bishop.(Glenn Beck)